On Jan. 6th, Peter Lowenstein observed a rainbow-colored saucer over Mutare, Zimbabwe--but it wasn't a UFO. "This is a classic example of a pileus cloud," he says.

Pileus clouds form on sunny afternoons when the heat of the summer sun causes cumulus clouds to boil upwards. Roiling toward the sky, cumulus clouds push layers of moist air above them where they cool and condense to form droplet-rich cloud caps or 'pileus' (Latin for cap).Sometimes, as in Mutare on Jan. 6th, pileus clouds form very quickly. In such cases their water droplets tend to be all the same size--the perfect condition for iridescent colors.

Lowenstein took four pictures over a period of just three minutes. "They show the cloud appearing, then changing shape and color," he says. "One minute later it had disappeared behind the summit of the growing cumulonimbus cloud."www.spaceweather.com

Earth's stratosphere is normally free of clouds. Not this weekend, though. Observers around the Arctic Circle are reporting an outbreak of brilliantly-colored icy clouds in the typically dry and transparent layer of our planet's atmosphere. Eric Fokke photographed the display on New Years Eve from the Lofoten Islands of Norway:

These icy clouds are a sign of very cold temperatures. For ice crystals to form in the arid stratosphere, temperatures must drop to around -85º C. High-altitude sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colors.Once thought to be mere curiosities, some polar stratospheric clouds (PSCs) are now known to be associated with the destruction of ozone. Indeed, an ozone hole formed over the UK in Feb. 2016 following an outbreak of ozone-destroying Type 1 PSCs.

These clouds really are as amazing as they look in Fokke's photo. They have much more vivid colors than ordinary iridescent clouds, which form closer to Earth in the troposphere. Once seen, a stratospheric cloud is never forgotten.www.spaceweather.com

During this week's solar wind event, observers around the Arctic Circle reported auroras of an unusual color. "Crazy pink," says Frank Meissner, who photographed the phenomenon on Oct. 26th from Tromsø, Norway:

"It was awesome," he says. "Flash-like bursts were zooming all over the sky."

Watching from Tromsø on the same night, veteran observer Terence Murtagh says "even with many hundreds of aurora sightings under my belt, I've never witnessed such distinct pink colors clearly visible and bright to the naked eye. They were almost too bright to photograph properly."

The pink color is probably a sign of nitrogen. Most auroras are green--a verdant glow caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth's surface. Seldom-seen pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below. More examples may be found in the realtime photo gallery:Realtime Aurora Photo Gallerywww.spaceweather.com

Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. The colors are usually pastel, but, as in these pictures, they can be very vivid. Newly forming clouds produce the brightest and most colorful iridescence.

Iridescence is generally produced near where the sun appears in the sky, with the sun's glare masking it, so it is more easily seen by hiding the sun behind a tree or building. In our case, it was hidden by the Andes. Other aids are dark glasses, or observing the sky reflected in a convex mirror or in a pool of water. Or one can simply block the sun (but not the cloud) with the palm of one's hand.

A few days before, this blood red sunset sky engulfed the smoggy sky of Santiago de Chile.

The stratosphere is a relatively clear layer of Earth's atmosphere, almost always cloud-free. Almost always. On Monday, researchers at Argentina's San Martín Base spotted a bank of fantastically colored clouds floating in the stratosphere above the Antarctic Peninsula:

"There were the biggest stratospheric clouds we've seen so far this year," says photographer "Marcelo," who is working at the Base this winter. "It was a colorful spectacle to begin the day."These are called "Polar Stratospheric Clouds" (PSCs). They form in the lower stratosphere when temperatures drop to around minus 85º C. This explains why they are rare; even at the poles, such low temperatures are hard to achieve. High-altitude sunlight shining through tiny (~10µm) ice particles in PSCs produce bright iridescent colors by diffraction and interference. Once thought to be mere curiosities, some PSCs are now known to be associated with the destruction of ozone. www.spaceweather.com

Seaside photographers have a special fondness for the sunset. On rare occasions they can catch the elusive green flash--a split-second pulse of verdant light that signals the disappearance of the sun beneath the ocean waves. On April 7th, astronomy professor Jimmy Westlake photographed a green flash as he stood atop Hawaii's Mauna Kea volcano. The flash he saw, however, did not come from the ocean waves. It happened in the clouds:

"The SKY Club from Colorado Mountain College got an emerald surprise," he says. "Several students visually witnessed the green flash while I was photographing it."

"This appears to be a cloud-top flash," says atmospheric optics expert Les Cowley. "They are not fully understood but might be produced by an inversion layer overlaying the clouds. We need more observations and associated weather data to understand them better."

Basically, a temperature inversion bends the sun's rays to form a mirage that vertically magnifies the tiny color separation which is always present at the edge of the setting sun. Indeed,in Westlake's flash, we see not only green, but also yellow, red, and even a wisp of blue. "The intensity of the blue-green flash caught everyone by surprise!" says Westlake.www.spaceweather.com

An annual pilgrimage by amateur and professional photographers to Yosemite National Park to capture a unique solar lighting effect has been revived with the recent wet weather.

For a couple of weeks in February, Yosemite's Horsetail Fall gets bathed in the light of the setting sun, creating what is known as a "firefall," with the waterfall and wet rockface creating an orange glow from the reflection. In recent years, a lack of water or cloudy weather has meant the spectacular effect does not appear during the brief window when the sun is aligned perfectly on the fall. This year, images of the firefall at Horsetail Fall has blanketed social media.

The history of the Yosemite Firefall began with a manmade firefall in the last 19th century, when a campfire at the top of Glacier Point was pushed over the edge of the cliff, treating spectators below to a fiery spectacle. It became an annual event that increased in size and popularity, until it was finally discontinued in 1968.

In 1973, close to the 100-year anniversary of the first Yosemite Firefall, a photographer captured the first known photo of the natural firefall at Horsetail Fall.

Carlos E. Castañeda is Senior Editor, News & Social Media for CBS San Francisco and a San Francisco native

A cloud that took the form of a 'hand of God' holding a fireball dominated the skyline above the north coast of the Portuguese island of Madeira. And weather blogger Rogerio Pacheco, 32, could not believe his luck when he looked up at the clouds while commuters made their way to work in the morning rush hour.

The awe-inspiring snaps have since been shared online after Rogerio opted to post them on his blog. Amazed onlookers have compared the bright orange cloud to everything from a flaming fist of fury to the iconic comet featured in the classic video game Final Fantasy VII.

Rogerio said: "As soon as I saw the sky, I was immediately intrigued and I just had to grab my camera to take a photo. For me, the cloud looks like an outstretched hand with a fireball. I was not the only one who seemed to notice it and I could see other people also looking up at the sky. A lot of people seemed pleasantly surprised when they looked up at the sky and saw the cloud."

If you have ever been privy to the phenomenon of light pillars, then you know it is truly an amazing sight. They appear when the weather is extremely cold and form vertical columns of light beaming directly towards the sky. Here a compilation of pillars of light for December 2015. They sometimes look like multiple fireballs heading to the sky:

Geomagnetic storms are brewing, but not every colorful light in the night sky is an aurora. For instance, Yuri Beletsky sends this picture taken Dec. 17th from the Atacama desert in Chile:

"These are not auroras. We just witnessed an amazing display of airglow," says Beletsky. "It was so intense that you could not see many stars close to the horizon - the sky was literally shining."

Airglow is an aurora-like phenomenon in the upper atmosphere caused by a variety of chemical reactions. It begins during the day when solar ultraviolet radiation ionizes atoms and molecules. At night, those same atoms and molecules glow as they re-capture lost electrons. The green in Beletsky's photo comes from oxygen atoms in a layer 90-100 km high; the red is probably associated with OH ions at an altitude of about 85 km. The wavy structure of the glow is due to high-altitude gravity waves, which alter the temperature and density structure of the upper atmosphere.

"Airglow is much less intense than aurora," continues Beletsky. "The display I saw looked, to the naked eye, like a series of black-and-white waving bands. The full color of the display was easily captured, however, by my digital camera."www.spaceweather.com

For the second day in a row, sky watchers are reporting an outbreak of polar stratospheric clouds (PSCs) around the Arctic Circle. Unlike normal grey-white clouds, which hug Earth's surface at altitudes of only 5 to 10 km, PSCs float through the stratosphere (25 km) and they are fantastically colourful. Truls Tiller photographed these over Tromsø, Norway, on Dec. 16th:

"Here the sun is gone for now," says Tiller, "but this beautiful view makes the winter darkness nice to be in as well. The picture was taken at 10.30 am, in the middle of the 'day.'"

Also known as "nacreous" or "mother of pearl" clouds, the icy structures form in the lower stratosphere when temperatures drop to around minus 85ºC. High-altitude sunlight shining through tiny ice particles ~10µm across produce the characteristic bright iridescent colours by diffraction and interference. Once thought to be mere curiosities, some PSCs are now known to be associated with the destruction of ozone.

"Nacreous clouds far outshine and have much more vivid colours than ordinary iridescent clouds, which are very much poor relations and seen frequently all over the world," writes atmospheric optics expert Les Cowley. "Once seen they are never forgotten." www.spaceweather.com

On September 15, 2015, witnesses filmed a very strange cloud phenomenon above Costa Rica at about 3.00 pm local time. We may wonder whether this strange cloud is just a natural phenomenon or a so-called earthquake light or there's more than our eyes can see?

Earthquake lights are reported to appear while an earthquake is occurring, although there are reports of lights before or after earthquakes. They are reported to have different shapes with a white to bluish hue, but occasionally they have been reported having a wider color spectrum.

The luminosity is reported to be visible for several seconds, but has also been reported to last for tens of minutes.

A different explanation involves intense electric fields created piezoelectrically by tectonic movements.

Another possible explanation is local disruption of the Earth's magnetic field and/or ionosphere in the region of tectonic stress, resulting in the observed glow effects from ionospheric radiative recombination at lower altitudes and greater atmospheric pressure.

Lunar eclipses are supposed to be red. This morning's eclipse had an extra dash of turquoise. "The colors on this eclipsed moon were more varied and vivid than any in memory -- maybe because it stayed so close to the edge of the shadow for the duration of the eclipse," reports astronomy professor Jimmy Westlake, who sends this picture from Stagecoach, Colorado: "Nearly every color of the rainbow appeared on the Moon just before the end of totality," he says. Atmospheric scientist Richard Keen of the University of Colorado explains the colors: "During a lunar eclipse, most of the light illuminating the Moon passes through Earth's stratosphere where it is reddened by scattering. However, light passing through the upper stratosphere penetrates the ozone layer, which absorbs red light and actually makes the passing light ray bluer." This can be seen, he says, as a soft blue fringe around the red core of Earth's shadow--colors which are reflected from the surface of the Moon.

Aurora Borealis 9-12-14 from Lights Over LaplandPlus On September 11th and 12th two CMEs interacted with Earth's magnetosphere, causing a KP-7 Geomagnetic storm. The storm sparked large aurora displays that will never be forgotten by the people that were lucky enough to witness the event. This short film is for everyone else....facebook.com/lightsoverlapland